Podcasts usually consist of audio, video, PDF, and/or ePub files that are published or broadcast online in a series of episodes. They can be downloaded using software known as a podcatcher and played or streamed by a media player. Though many podcasts are paid for using a subscription, many are also accessible for free. Often a user accesses a podcast through a web-feed link on a “wall” webpage (e.g., MyYahoo!) associated with a user.
Facebook, Twitter, Google+, and other social networking websites present items of content including text, images, and videos to their users using a content stream that is in reverse-chronological order (e.g., with the topmost item in the stream being the last in time) or ordered according to an interestingness algorithm (e.g. with the topmost item in the stream having the highest interestingness score according to the algorithm) and/or a personalization algorithm. Such content streams are now also used by content-aggregation websites such as Yahoo! News and Google News.